GD,
It appears my memory is intact. In Bruce Buck's SSM article from the May/June 07 mag. he states that Lou of CSMC. told him that his gun, which was used for the article, had a mil-spec thermal-set coating. Buck's gun has a SN of under 100. It would be interesting to know at what point CSMC switched to the "Belgian" process.
Don't worry about the staining. If you like the gun on clays you're going to love it in the field. I had three go to guns and that's after a lot shotguns. Now it's four.

Fred